Reversible pitch fan



Oct. 20, 1959 H. CROSS ET REVERSIBLE PITCH'F'AN Filed Aug. 8, 1956INVENTORS JAMES A. MIDGLEY HARRE L GROSS ATTORNEY 2,909,229 REVERSIBLEPITCH FAN Harrel Cross, Fort Myers, and James A. Midgley,

' Fort Myers Beach, Fla.

Application August 8, 1956, Serial No. 602,843

1 Claim. (Cl. 170-16024) This invention relates to fans, and itparticularly relates to fans having blades the pitch of which can beadjusted.

There are many dilferent situations where the pitch of the blades of afan must be reversed. One such instance is in the case of earth movingequipment such as United States Patent bulldozers, draglines, and thelike. It has been common "1 practice to carry two cooling fans ofopposite pitch in such equipment so that when the radiator becomesfouled by sand, dust, leaves and dirt sucked up by the fan, the fan isremoved from the shaft and the fan of opposite pitch is attached. Whenthis opposite pitch fan is then actuated, the accumulated fouling matteris blown out.

Among the great disadvantages of this prior system, consisting of theuse of two opposite pitch fans, is the fact that it generally takes atleast an hour or more of arduous labor to remove one fan and replace itwith the other. As a result, there is a tendency to omit changing thefans as often as necessary, especially when the equipment is hot fromheavy use. This often leads to damage of the engine since the fan is,when fouled, not capable of providing a suflicient cooling effect.

It is one object of the present invention to overcome the abovedisadvantages by providing a fan construction, the pitch of which can beeasily adjusted or reversed without the necessity of any bodilyreplacement.

Another object of the present invention is to provide a fan ofreversible pitch wherein the pitch can be reversed in seconds withoutany necessity for using tools or other handling equipment and withoutany undue labor.

Another object of the present invention is to provide a reversible pitchfan wherein the pitch can be reversed simply, easily and almostinstantaneously.

Other objects of the present invention are to provide an improved fan,of the character described, that is easily and economically produced,which is sturdy in construction, and which is highly eflicient inoperation.

With the above and related objects in view, this invention consists inthe details of construction and combination of parts, as will be morefully understood from the following description, when read inconjunction with the accompanying drawing in which:

Fig. 1 is a front elevational view of a fan device embodying the presentinvention.

Fig. 2 is a top plan view of the device of Fig. 1.

Fig. 3 is a fragmentary top plan view showing the device at the timewhen the pitch is being reversed.

Fig. 4 is a fragmentary top plan view showing the device after the pitchhas been reversed.

Fig. 5 is a front elevational view of one of the blades when removedfrom the fan device.

Fig. 6 is a front elevational view of one of the pivot rods used inconjunction with the blades.

Referring now in greater detail to the drawing wherein similar referencecharacters refer to similar parts, there is shown a fan device,generally designated 10, compris- 2,909,229 Patented Oct. 20, 1959 ing apair of coaxially-spaced rings 12 and 14. Each of the rings is providedwith a plurality of sockets, here shown as six in number, such socketsbeing indicated at 16 on ring 12 and 18 on ring 14. The sockets on eachring are circumferentially spaced from each other by equal arcuatedistances. At the same time, in their normal positions, the sockets 16are also circumferentially ofiset from the sockets 18. 3

These rings 12 and 14 surround a hub 20 having a central opening 22adapted to receive a shaft, not shown. The hub 20 is also provided witha plurality of sockets 24, equal in number to the sockets on each ring,these sockets 24 being provided on the external periphery of the hub.

Positioned between the two rings 12 and 14, on the one hand, and the hub20, on the other hand, are a plurality of radially-extending,circumferentially-spaced blades 26. Each of these blades may be providedwith a relatively wide, arcuate outer edge 28 and a relatively narrowinner edge 30. The side edges 32 of each blade may taper inwardly fromthe outer to the inner edge. The blades are constructed of sheet metalwhich may have substantial flexibility while the rings are rigid; or,vice versa, the blades may be substantially rigid, and the rings may beof substantial flexibility.

Connected to the outer edge of each blade 26 are a pair of rods or pins34 and 36, the pins 34 being closer to one edge 32 and the pins 36 beingcloser to the other edge 32 of each of the blades. These pins 34 and 36are connected to the blades by any convenient means such as the rivetsindicated at 38. The pins, themselves, are preferably provided withrecesses 40 which interengage with recesses 42 in the arcuate edges ofthe blades. The bodies of the pins extend down below these recesses andare provided with holes 44, adapted to mate with holes 46 in the blades,to receive the rivets 38. The opposite ends of each of the pins 34 arereceived in a corresponding socket 16 in the ring 12 while the oppositeends of each of the pins 36 are received in corresponding sockets 18 inthe ring 14.

The inner edges of the blades are connected to the hub 20 by means ofrods or pins 48 attached, at one end, to the blades by means ofinterengaging groo ves similar to grooves 40 on pins 34 which engagewith recesses 50 on .the inner edges of the blades, and rivets 52 or thelike, which extend through holes in pins 48, similar to those of pins34, and through holes 54 in the blades. The opposite ends of the pins 48are received in sockets 24 in the hub.

Since the leading edge portion of each blade is connected to one ringwhile the trailing edge portion is connected to the other ring by meansof their respective pivot pins 34 and 36, when the rings are rotated inopposite directions,'all the blades turn in unison and force the ringsaxially away from each other until they reach the extreme positionindicated in Fig. 3. Thereafter, as the rings are continued to berotated contra to each other, the blades turn into the reverse angle orpitch and the rings come closer together again. The pitch of the bladesis now reversed.

The pitch of the blades can also be reversed by simply turning oneblade. The movement of the one blade will act simultaneously on all theothers through the rings 12 and 14, and the same movement as describedabove will take place.

As the blades are rotated from one pitch to the opposite pitch, theangle between the pivot pins 34 and 36 on blades 26 and the sockets 16on ring 12 and sockets 18 on ring 14 must necessarily change from astress free condition when in either pitch to an increasingly stressedcondition as the blades are rotated outwardly to the center point, andthen the stressed condition assists in rotating the blades beyond thecenter point back to the stress free condition to thus retain the bladesblocked in fan operating position.

The pins being fairly tight in their sockets, either the blades mustyield or bend slightly between the pins on each blade, or the rings mustbend or yield slightly in an outward direction from each other, withtheir outer peripheries moving further away from their inner peripheriesfrom each other, or both may bend or yield slightly, depending on therelative strength of the material of the rings and the blades. Thisbending or yielding is slight and within the elastic limits of thematerial, hence it resists the movement until the center point ispassed, then it assists the movement until normal pitch is reached andthus tends to hold or lock the blades in either normal pitch.

Although this invention has been described in considerable detail, suchdescription is intended as being illustrative rather than limiting,since the invention maybe variously embodied, and the scope of theinvention is to be determined as claimed.

Having thus set forth and disclosed the nature of this invention, whatis claimed is:

In a rotatable fan construction, a hub having an outer 4 rim and aplurality of equidistantly spaced peripheral sockets in said outer rim,a pin rotatably mounted in each socket, a substantially sector shapedflexible blade secured to each pin at its smaller end, a pair of pinsfixed to the outer end of each blade in spaced relation, a pair offlexible rings, each having an inner rim coaxial with said hub extendingabout the outer ends of said blades, the inner rim of each ring having aplurality of sockets therein, the sockets of each ring rotatablyengaging one of each of said pairs of pins on the outer ends of saidblades, said blades being of width at their outer ends of slightly lessthan the length thereof, said pair of pins on the outer end of eachblade being located on radii extended from the axis of rotation of saidfan a suflicient distance on opposite sides of the radius of the pin onthe smaller end of the blade whereby the resiliency of said blades andrings serves to retain the pin on the smaller end of the blades in apreset position of angular adjustment.

Longauer Nov. 19, 1895 Artibee Jan. 5, 1915

